The use of carboxylated/sulfonated polymers in automatic dishwashing is known (DE 102 33 834, U.S. Pat. No. 5,547,612). These polymers help with the cleaning and at the same time provide anti-filming and anti-spotting benefits, in particular on glassware. An example of the use of this kind of polymers, in liquid form, in automatic dishwashing can be found in EP 1,404,790 B1, which relates to a liquid aqueous machine dishwashing product comprising a carboxylated/sulfonated polymer.
US 2004/0116319 discusses problems associated with carboxylated/sulfonated polymers in liquid form. The polymers in liquid form can only be processed with great difficulty, since the corresponding solutions are considerably tacky and impair the formation of homogeneous, flowable mixtures. In addition, particulate products into which the polymer has been incorporated from a liquid delivery form have a tendency to clump, thus lowering consumer acceptance, while tableted products have problems such as after-curing and poor dissolution properties.
'319 addresses the problem of providing a solid machine dishwashing agent that comprises carboxylated/sulfonated polymers without giving rise to product problems such as clumping, after-curing or poor dissolution properties. The problem is allegedly solved by the use of the carboxylated/sulfonated polymers in particulate form wherein at least 50% by weight of the polymer have a particle size greater than 200 μm. Carboxylated/sulfonated polymers are physically instable, particularly, under manufacturing plant conditions. The polymers, even when they have the particle size proposed in '319, can form a non-flowable glue-like material that it is very difficult to process. Thus, one of the objectives of the present invention is to overcome the in-plant processability and storage issues associated to carboxylated/sulfonated polymers. '319 concerns the stability of carboxylated/sulfonted polymers in a detergent product. The present invention concerns the stability of carboxylated/sulfonted polymers when they are stored in bulk and they are used as raw material in a detergent making process.